roundn

Round a numeric value to the nearest multiple of 10^n.

Usage

var roundn = require( '@stdlib/math/base/special/roundn' );

roundn( x, n )

Rounds a numeric value to the nearest multiple of 10^n.

// Round a value to 2 decimal places:
var v = roundn( Math.PI, -2 );
// returns 3.14

// If n = 0, `roundn` behaves like `round`:
v = roundn( Math.PI, 0 );
// returns 3.0

// Round a value to the nearest thousand:
v = roundn( 12368.0, 3 );
// returns 12000.0

Notes

  • When operating on floating-point numbers in bases other than 2, rounding to specified digits can be inexact. For example,

    var x = 0.2 + 0.1;
    // returns 0.30000000000000004
    
    // Should round to 0.3...
    var v = roundn( x, -16 );
    // returns 0.3000000000000001
    

Examples

var randu = require( '@stdlib/random/base/randu' );
var roundn = require( '@stdlib/math/base/special/roundn' );

var x;
var n;
var v;
var i;

for ( i = 0; i < 100; i++ ) {
    x = (randu()*100.0) - 50.0;
    n = roundn( randu()*5.0, 0 );
    v = roundn( x, -n );
    console.log( 'x: %d. Number of decimals: %d. Rounded: %d.', x, n, v );
}